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CONCLUSIONS AND RECOMMENDATIONS In summary, the soil conditions examined near the existing septic system drain field were found to be suitable for standard septic systems utilizing leach lines and seepage pits. A satisfactory soil percolation rate of 4.16 min/in was observed in the shallow soil zone at the test location. The depth of ground water based on recent aquifer levels is approximately 140 to 150 feet below ground surface. Ground water flows to the south or south-southeast in the area at a rate of approximately three feet per mile. The highest recent ground-water levels for the area were experienced in 1983 and 1999, when depth to water would have been approximately 120 to 125 feet. Because the percolation rate encountered falls between 1.0 and 5.0 min/in, the San Joaquin County Environmental Health Department will require a 20-foot separation from the bottom of the dispersal system to ground water. Based on the depth to ground water in the area, no modification to standard systems should be required. A water sample was collected from the domestic well on the Site as part of this investigation. Nitrate was detected in the sample at a concentration of 1.5 mg/L-N, well below the MCL of 10 mg/L-N. DBCP was not detected in the sample; the MCL for DBCP is 0.2 ug/L. Based on a review of the San Joaquin County Environmental Health Department map of nitrate detections in County wells, one well within a one-mile radius of the Site was tested; nitrate was detected at a concentration between 0.1 and 5.0 mg/L-N. According to the DBCP map, one well within a one-mile radius was tested; DBCP was not detected. Based on the current project, the use of on-site septic tanks and drain field systems on the Site is not expected to cause a buildup of nitrate in the aquifer above 1.2 mg/L-N. This level falls below the US EPA drinking water recommendation of 10 mg/L-N. We believe the Site suitable for the use of standard septic systems. Based on the satisfactory result of the nitrate loading calculation, no nitrate mitigation is recommended. LOGE 1913 Page 14